Species: Lontra canadensis

North American River Otter
Species

    Articles:

    Marine-foraging river otters in the Salish Sea

    While not true marine mammals, river otters do use and rely on marine resources. The expansion of their populations since the early 1900s is a true conservation success story. Ecosystem recovery efforts and river otter reintroductions restored otter populations to much of their historic range. River otters often live in small social groups that include mother and offspring or other unrelated adults.

    River otters on a dock in Puget Sound
    Causes of mortality in marine-foraging river otters

    North American river otters (Lontra canadensis) inhabit inland freshwater environments; however, from Alaska to California they also occur in coastal marine waters where they forage on a variety of marine fish and invertebrates. Little is known about mortality factors in marine-foraging river otters. Among 30 otter carcasses collected in San Juan County, Washington, analysis indicates that car collisions and gunshots were the most common causes of mortality.

    Otter crossing street sign. Photo: Joe Gaydos
    Spatial and Temporal Variation in River Otter (Lontra canadensis) Diet and Predation on Rockfish (Genus Sebastes) in the San Juan Islands, Washington

    A 2014 paper in the journal Aquatic Mammals examines coastal river otter predation on rockfish at three islands in the Salish Sea.

    River otter with crab. Photo courtesy of the SeaDoc Society.
    Kingdom
    Animalia
    Phylum
    Craniata
    Class

    Mammalia

    Order

    Carnivora

    Family

    Mustelidae

    Genus

    Lontra

    Classification
    Other Global Common Names
    North American Otter - Northern River Otter - River Otter - loutre de rivière
    Informal Taxonomy
    Animals, Vertebrates - Mammals - Carnivores
    Formal Taxonomy
    Animalia - Craniata - Mammalia - Carnivora - Mustelidae - Lontra - Patterns of genetic variation do not concur with current subspecific designations (Serfass et al. (1998), and numerous translocations have crossed subspecies' range boundaries; hence the use of subspecific names is not meaningful in many cases.
    Short General Description
    A large mustelid (otter).
    Habitat Type Description
    Freshwater
    Migration
    true - false - false
    Non-migrant
    true
    Locally Migrant
    false
    Food Comments
    Feeds opportunistically on aquatic animals, particularly fishes (mostly slow-moving, mid-size species), frogs, crayfish, turtles, insects, etc., sometimes birds and small mammals. In coastal waters eats marine species (Bowyer et al. 1995). Commonly preys on nesting seabirds in some areas (e.g., Alaska islands). See Toweill and Tabor 1982 for many further details.
    Reproduction Comments
    Implantation is delayed 8 months or more. Gestation, including delayed implantation, lasts 9-12 months. In many areas, births peak in late winter-early spring; parturition dates may not be closely synchronized within a given population. Litter size is 1-6 (average 2-3); 1 litter per year. Young may first enter water at about 7 weeks, are weaned at about 3 months, stay with mother for about a year. Male may rejoin family after young leave den. Females breed for the first time at 2 years. Males become sexually mature at 2 years, but may not breed successfully until 5-7 years old. Females evidently breed in alternate years in some areas (e.g., Alabama, Georgia), every year in Oregon (see Toweill and Tabor 1982).
    Ecology Comments
    Home range typically is linear; 20-30 miles for a pair or male; less for females with young (Jackson 1961). May hunt over as much as 80-100 km of stream during the course of one year. In coastal Alaska, summer home range size averaged around 20 km of shoreline in males, 10 km in females, with ranges twice as large in oiled areas (Bowyer et al. 1995). <br><br>Population density of one per 2.2 miles has been recorded (Baker 1983). Density was estimated at one otter per 86 ha of coastal marsh in Louisiana (Shirley et al. 1988). In Idaho, density was one family group and 1-3 subadults or nonbreeding adults per 15 km of waterway, plus one breeding adult male for each 20-30 km of waterway (see Toweill and Tabor 1982). Density in coastal areas of the Gulf of Alaska was 0.30-0.85 otters/km of shoreline (Testa et al. 1994, Bowyer et al. 1995).
    Length
    131
    Weight
    13600
    NatureServe Global Status Rank
    G5
    Global Status Last Reviewed
    1996-11-18
    Global Status Last Changed
    1996-11-18
    Conservation Status Map
    <img src="http://www.natureserve.org/explorer/servlet/GetMapGif?CA.AB=S3&CA.BC=S4&CA.LB=S5&CA.MB=S5&CA.NB=S5&CA.NF=S5&CA.NT=S4&CA.NS=S5&CA.NU=SNR&CA.ON=S5&CA.PE=SX&CA.QC=S5&CA.SK=S5&CA.YT=S4&US.AL=S4&US.AK=S5&US.AZ=S1&US.AR=S5&US.CA=SNR&US.CO=S3&US.CT=S5&US.DE=S4&US.DC=S1&US.FL=SNR&US.GA=S5&US.ID=S4&US.IL=S2&US.IN=S2&US.IA=S3&US.KS=S3&US.KY=S3&US.LA=S4&US.ME=S5&US.MD=S5&US.MA=S4&US.MI=S4&US.MN=SNR&US.MS=S4&US.MO=S3&US.MT=S4&US.NN=S1&US.NE=S2&US.NV=S2&US.NH=S5&US.NJ=S4&US.NM=SH&US.NY=S5&US.NC=S4&US.ND=S1&US.OH=S3&US.OK=S2&US.OR=S4&US.PA=S3&US.RI=S4&US.SC=SNR&US.SD=S2&US.TN=S3&US.TX=S3&US.UT=S3&US.VT=S5&US.VA=S4&US.WA=S4&US.WV=S1&US.WI=S4&US.WY=S3" alt="Conservation Status Map" style="width: 475px; height: auto;" />
    Global Range
    FG - 20,000-2,500,000 square km (about 8000-1,000,000 square miles) - FG - Throughout most of North America north of Mexico, except the extreme southwestern U.S. Extirpated from large areas of the interior U.S. following European colonization. Has been reintroduced in some parts of the range (e.g., Colorado, Virginia).
    Global Range Code
    FG
    Global Range Description
    20,000-2,500,000 square km (about 8000-1,000,000 square miles)
    ELEMENT_GLOBAL.2.102243